Special Containment Procedures: All aviary species found to be part of SCP-1608's diet are to be maintained in an aviary within Area-78. Satellite footage of this area is to be scrubbed by Foundation personnel.

Members of MTF-Kappa-11 "Red Barons" are to track and monitor SCP-1608's current location and report its status to Area-78. Airborne personnel are to maintain a distance of 150 meters away from SCP-1608's estimated location, to prevent their crafts from being damaged during containment events. Seaborne personnel are to report any manifestation events they observe. If containment is breached, members of MTF-Kappa-11 are to follow its hypothesized location until it manifests, then release food for it in a trail leading back to Area-78.

Description: SCP-1608 is a Baleonoptera musculus, or blue whale, located between 50-110 meters above the earth's surface. It is estimated to weigh 154 metric tonnes and has a length of 29 meters. Its flipper has been imprinted with a stylized image resembling clouds. Further observation has been hampered by SCP-1608's anomalous property.

SCP-1608 is intangible, and will spend most of its time drifting through the atmosphere. It appears to have limited control over its movement, and will attempt to steer itself towards food and objects it believes to be food. During this time, SCP-1608 is impossible to observe, as all methods of tracking airborne bodies have proven ineffective. SCP-1608 manifests physically once every half hour, and will remain corporeal for a period between 16-20 seconds before returning to intangibility. It is hypothesized that SCP-1608 manifests to breathe and excrete waste.

When feeding, SCP-1608 will move itself so that its prey is situated within its intangible stomach, then re-manifest for a period between 1-3 seconds to consume it. This effect will also cause any other solid matter within its form to be taken into SCP-1608's body. Prior to containment, SCP-1608 caused the near extinction of several high-atmospheric birds due to its rapid consumption of these animals.

In addition, any other matter taken into SCP-1608's body that is not consumed will be released from its body some point after being taken inside. There appears to be no upper limit to the amount of matter SCP-1608 is capable of holding, and no additional space appears on its body to compensate for this additional mass. Artifacts dating back to as early as 1776 have been discovered originating from its mass.

SCP-1608 was first observed by the Foundation on 8/11/1929, after reports of several whaling ships sighting of a "massive airborne whale" reached Foundation agents embedded in Tokyo, Japan. Subsequent sightings provided cause for a Foundation investigation, however all investigation into the anomaly was suspended due to budgetary concerns.

Containment began in 1976, after personnel in Tokyo rediscovered the original reports and alerted local command to the anomaly. After brief scouting missions to the previously reported area, the anomaly was confirmed and containment procedures were enacted. As of 03/19/1980, SCP-1608 has been classified as Euclid.

Addendum: Log of items consumed and produced by SCP-1608.

Date

Materials absorbed or consumed.

??/??/1928

Reported from original documentation. Consumed a portion of a whaling ship. Note that this is the lowest atmospheric levels reported from SCP-1608 activity.

12/19/1976

Took one Foundation aircraft which had been scouting the area SCP-1608 was reported to inhabit. The pilot, Agent Byrne, was reported as MIA.

03/11/1980

Expelled materials appearing to belong with a British whaling ship, including a watch tower, circa 1898. The remains of an unidentified human was found preserved with the watch tower, and the subject appeared to have expired upon exiting SCP-1608.

05/27/1982

Expelled approximately 324 members of the bird species ██████ ████, which had been extinct since 1900. All instances of ██████ ████ were contained at Area-78's aviary.

08/19/1991

Flag originating from a Spanish vessel dating from at least 1776 was expelled from SCP-1608. Appeared to be drenched in SCP-1608's blood, however no damage was noted on SCP-1608.

07/07/1999.

The remains of a Foundation aircraft and Agent Byrne were released. Autopsy showed Agent Byrne was killed upon exiting SCP-1608. No other abnormalities were noted with the body or aircraft.